well the subs are pretty easy to access... four bolts connect seat to floor... lean seat back and viola - access to subs.... check for yourself.... test the leads on sub with volt meter on ohm setting or continuity.... check cable from amp for voltage (presence of signal) (while audio is on).. hook up sub to another source see if it works at all (dont keep it on another source for long, impedance mismatch can damage speaker and amp) and wrong frequencies not good for sub... try another sub to connections to car amp... \

even if subs were "blown" you will still get sound but distorted as hell... usully spyder becomes disconnected from cone or coils burn out.... the latter could cause no sound (which is what continuity test is for)

Thanks for the quick response. What size subs are under the seat and whats the ohm load on them?